TIPS dysfunction refers to the narrowing or blockage of the stent caused by either intimal hyperplasia or in-situ thrombosis, typically occurring in the cephalic portion of the stent. It is crucial to monitor TIPS closely due to the high incidence of stent stenosis, which ranges from 8% to 20% of patients within the first year. This condition is associated with significant morbidity and mortality due to the recurrence of portal hypertension complications. Early diagnosis of TIPS dysfunction has been shown to reduce the incidence of variceal bleeding and recurrent ascites².

Doppler ultrasound is a valuable tool for screening TIPS, while venography should be performed to confirm the status of the stent². The first study should not be done within the first month due to the air artifacts of polytetrafluoroethylene³.

The study system to be followed for the proper performance of the ultrasound scan is as follows⁴:

• B-mode ultrasound:
• Signs of portal hypertension.
• Focal hepatic lesions.

• Doppler ultrasound: 
• Portal vein: patency, direction and maximum portal flow velocity.
• TIPS: location, caliber, patency and maximum flow velocity.
• Patency of the splenoportal axis and splenic vein.
• suprahepatic veins
• Hepatic artery.

Radiologists must be familiar with ultrasound findings of normal TIPS (figure 2, table 4), and recognize the various findings of stent dysfunction (table 5). The lack of Doppler flow within the stent (figure 3), a TIPS flow velocity over 190 cm/s (figure 4) or under 90 cm/s, and the decrease of the portal vein velocity under 30 cm/s (figure 5) are findings that suggest the oclussion of the stent³.